This invention relates to lattice panel bridges and more particularly to the pin connections by which adjoining lattice panel bridge members are coupled together.
Conventionally lattice panel bridge members are coupled together by pins which have tapered ends or by bolts. When such a pin is driven it acts in the manner of a drift and automatically corrects misalignment of the holes in the sheaves of the members which are to be coupled together. Apart from this however it is necessary to maintain axial tension in the pin and to ensure that it neither loosens under the effect of vibration, nor rotates to a skew attitude between the two sheaves carrying opposing forces.
Conventionally, the pin is retained by use of a safety pin, or split pin or a circlip. None of these expedients however apply any axial tension or cause any frictional force between the sheaves.
The most efficient mode of applying tension and friction is to insert a wedge through a slot in the pins but the conventional wedge is uniplanar and relies solely on jamming friction to prevent loosening.
A further difficulty with the use of a conventional pin and wedge coupling arrangement is that the aggregated thickness of the sheaves to be coupled together can only vary by the difference between the maximum and minimum thickness, - that is to say the angle of taper, of the wedge.